Yarn-connecting devices of the afore-described type are known, for example, from German Patent Publication DE 195 10 171 A1.
With these devices, an automatic yarn-connecting and/or cop-changing device is activated via the winding station computer of the respective winding station of the cheese-producing machine in case of a yarn break or a change of the delivery bobbin. More specifically, a suction nozzle is first placed against the surface of the take-up bobbin which is caused to slowly rotate in a direction opposite the winding direction. After the suction nozzle has grasped the yarn end trailing from the take-up bobbin (often referred to as the "upper yam end"), the suction nozzle is pivoted back into its initial position, in which the aspirating nozzle opening is positioned below a splicing device.
A gripper tube positioned in a lower initial position is pivoted almost simultaneously with the suction nozzle into an upper work position and in the process carries along a leading yarn end drawn off the delivery bobbin (often referred to as the "lower yarn end") which had been held in a fixed position up to that time, for example, in a yarn tenser.
On its end, the gripper tube has a pivotably seated gripper tube flap, which is biased into a closed position for example by a spring force, and has a yarn placement hook. In the course of upward pivoting, the gripper tube intersects the path of the trailing upper yarn end from the take-up bobbin with the yarn placement hook in order to also engage and carry this yarn, and the gripper tube then positions both yarn ends in the splicing device in a functionally correct manner to be pneumatically spliced together. More specifically, the gripper tube flap, which mechanically fixes the bottom yarn in place via its gripper tube flap and takes along the top yarn via its yarn placement hook during the upward pivoting of the gripper tube, is slightly opened by means of an appropriately curved element when the gripper tube enters its terminal position, so that the two ends of yarn are placed into the splicer in a tensioned manner.
Following the cutting of excess portions of the two yarn ends by appropriate cutter devices of the splicer, the cut excess portion of the bottom yarn is aspirated off by the gripper tube. Thereafter, the gripper tube is pivoted back into its initial position. In the course of downward pivoting of the gripper tube, the gripper tube flap, which is still guided on the curved element, initially remains in a position in which the mouth of the gripper tube is at least partially open. Only after the gripper tube has disengaged from the curved element does the gripper tube flap close the mouth of the gripper tube either under the influence of the prevailing suction acting through the gripper tube or of via the aforementioned spring biasing element.
A disadvantage of this embodiment of the gripper tube is the danger that, in case of a yarn break or an intentional yarn cut by a cleaning device at the winding station which occurs while the gripper tube flap is still held open by the curved element, the gripper tube could aspirate the yarn during the downward movement. If the yarn is then again aspirated underneath the yarn tenser during the ensuing yarn break or cleaning operation which will be immediately initiated, winding of the yarn around the flap of the gripper tube can occur, which results in considerable trouble at the yarn-connecting device.